Lightweight walkers made of aluminum or magnesium are widely used to assist physically impaired persons in walking from place to place. Typically, such walkers comprise an open-sided frame, which is entered from the rear. The frame is self-standing on four legs, and has side rails or arms on it, which conveniently underlie the forearms and elbows of the user. The frame also includes a front bar which the user grasps with his or her hands to lift the walker and rock it from one position to another. When the walker is rocked forward, the user leans on the side rails or arms and steps into the walker, and it is moved forward again, with the sequence being repeated. Many such walkers have telescoping legs; so that the height of the walker may be adjusted to conform to the physical characteristics of the person using the walker.
Although walkers of the type described above are highly suitable for traversing horizontal or nearly horizontal surfaces, they cannot be used on stairways, because they either must be rocked backward or forward in order to place two of the legs on a higher step of the stairway while the other two legs (either the front or the back legs) are placed on a lower step. When this is done, standard walkers are highly unstable and unsafe to use.
Attempts have been made to develop walkers which are adjustable; so that the walkers may be used to negotiate stairs. Two such walkers are disclosed in the U.S. Pat. No. 3,387,617 to Reiber and U.S. Pat. No. 4,777,973 to Nakajima. Both of these patents disclose mechanisms for adjusting the relative lengths of the front and rear legs of the walker to permit stairs to be negotiated using the walker. In both of these patents, the adjustment is effected from the position of use by operating levers located near or at the top of the walker frame.
The device of Nakajima has telescoping legs in each of the four leg positions. The frame, which supports the legs, is a hollow pipe; and spherical balls fill the pipe between the tops of the two legs on each side. An adjustment lever located in the top side rail normally is inserted between adjacent pairs of balls to keep them from moving in either direction. When stairs are to be negotiated, the lever is pulled out of the path of the balls, and the walker is tipped forward or backward to obtain the desired relative lengths of the front and rear legs. When the desired length is achieved, the lever is depressed, and inserted between adjacent balls once again to hold them in place. Although this apparatus provides a relatively straightforward means of adjusting the relative lengths of the legs when pressure is applied to them, the device requires a frictional fit to prevent the legs from sliding to their most extended position when the walker is lifted or raised to negotiate the next step, or when the walker is used on the level. This requirement is a significant disadvantage, since such a frictional engagement typically will loosen in time; so that it becomes difficult for a physically impaired person to use the device, or at least to use the device with any degree of confidence.
The patent to Reiber has an adjustment provision for the front legs only. A thumb-actuated cam locking control is provided to lock (and, subsequently, to release) telescoping front legs of the walker into the desired position. The adjustment is made of the legs on both sides of the walker simultaneously.
Additional walkers have been patented, which employ telescoping legs to permit adjustment of the relative lengths of the front and rear legs for use of the walker on stairs. Devices of this type are shown in the U.S. Pat. No. 3,176,700 to Drury; U.S. Pat. No. 3,421,529 to Vestal; U.S. Pat. No. 3,455,313 to King; and U.S. Pat. No. 3,800,815 to Birk. All of the devices of these patents require individual adjustments to each of the legs at a point near the lower end of the legs. Such adjustments usually are difficult to make for a physically impaired person. In addition, the requirement for each of the four legs to be individually adjusted is a significant disadvantage to the use of the walkers disclosed in these patents.
Another disadvantage of all of the walkers of the patents discussed above is that the adjustment of the legs simply is effected by extending, collapsing or telescoping the legs, which otherwise extend in a fixed position from the upper support surface of the walker. Thus, when the walker is placed at an angle on a stairway, the stability of the walker is less than its stability on level ground, since the center of gravity, with respect to the contact point of the legs, moves from the center of the walker to a point which is generally closer to the forward legs on the walker when it is used to descend stairs, and closer to the rear legs when the walker is used to ascend stairs.
It is desirable to provide a walker which is readily adjustable to ascend or descend stairs, which readily may be operated by a physically impaired person from a normal position or use of the walker, and which provides greater stability in use than the devices of the prior art.